Iconicity, i.e. resemblance between form and meaning, is a widespread feature of natural language vocabulary (Perniss, Thompson, & Vigliocco, 2010), and has been shown to facilitate vocabulary acquisition (Imai, Kita, Nagumo, & Okada). But what kind of advantage does iconicity actually give? Here we use cross-situational learning (Yu & Smith, 2007), to address the question for sound-shape iconicity (the so-called kiki-bouba effect, Ramachandran & Hubbard, 2001). In contrast to Monaghan, Mattock, and Walker (2012), Experiment 1 suggests that the iconicity advantage comes from referential disambiguation rather than more efficient memory encoding. Experiments 2 and 3 replicate this result, and moreover show that the kiki-bouba effect is roughly equally strong for sharp and rounded shapes, a property that classic experiments were unable to confirm, and which has implication for the effect’s mechanism.